98 PERFORMANCE OF THE ENGINE. CHAP. VI. 



was of wrought iron, round which was a chamber ex- 

 I tending back to the feed-pumps, for the purpose of 

 .heating the water previous to its injection into the 

 boiler. The engine had no springs whatever, and was 

 mounted on a wooden frame supported on four wheels. 

 In order, however, to neutralise as much as possible the 

 jolts and shocks which such an engine would necessarily 

 encounter from the obstacles and inequalities of the 

 then very imperfect plateway, the water-barrel which 

 served for a tender was fixed to the end of a lever and 

 weighted, the other end of the lever being connected 

 with the frame of the locomotive carriage. By this 

 means the weight of the two was more equally dis- 

 tributed, though the contrivance did not by any means 

 compensate for the total absence of springs. 

 1 1 The wheels of the locomotive were all smooth, Mr. 

 \ Stephenson having satisfied himself by experiment that 

 Ithe adhesion between the wheels of a loaded engine and 

 the rail would be sufficient for the purpose of traction. 

 Robert Stephenson informed us that his father caused a 

 number of workmen to mount upon the wheels of a 

 waggon moderately loaded, and throw their entire 

 weight upon the spokes on one side, when he found that 

 the waggon could thus be easily propelled forward 

 without the wheels slipping. This, together with other 

 experiments, satisfied him of the expediency of adopting 

 smooth wheels on his engine, and it was so finished 

 accordingly. 



The engine was, after much labour and anxiety, and 

 frequent alterations of parts, at length brought to com- 

 pletion, having been about ten months in hand. It was 

 placed upon the Killingworth Railway on the 25th of 

 July, 1814 ; and its powers were tried on the same day. 

 On an ascending gradient of 1 in 450, the engine 

 succeeded in drawing after it eight loaded carriages of 

 thirty tons' weight at about four miles an hour ; and 

 for some time after it continued regularly at work. 



